Tuning device



Nov. 4, 1958 F. w. SCHMIDT, JR, ETAL. 2,359,420

TUNING DEVICE Original Filed June 20, 1951 Fig. l

ATTORNE Y5 United States Patent 1 2,859,420 TUNING DEVICE Originalapplication June 20, 1951, Serial No. 232,537, now Patent No. 2,767,381,dated October 16, 1956. Divided and this application February 29, 1956,Serial No. 568,954 1 Claim. (Cl. 336-77) This invention relates to anelectric tuning element for resonating radio frequency energies atvarious selectable frequencies, particularly useful for television.

This application is a division of our issued Patent No. 2,767,381 issuedon October 16, 1956.

It is among the objects of the invention to provide a tuner for radiofrequency energies which is compact, easily constructed, economical,which has a wide tuning range, and which avoids the use of slidingcontacts. Other objects will be apparent.

Figure 1 is a top elevational view of an alternative embodiment of theinvention.

Figure 2 is a cross-sectional view through 2-2 of Figure 1.

- Modifications of the shape of the tuning elements on the surface ofthe rotatable cylinder are shown in Figures 1 and 2. As illustrated, oneelement 47 may be substantially square in shape. A second element 48 hasa longer dimension circumferentially about the surface of the cylinder17. A third tuning element 49 may be relatively small in area ascompared to the other tuning elements on the cylinder. A fourth tuningelement 50 may be used having a different dimension or shape, dependingupon the particular tuning and tracking desired. A fifth tuning element51 is shown comprising a threaded metallic element which when rotatedwill move radially so as to vary in its radial position relative to theouter surface of the cylinder 17.

Although the rotatable tuning cylinder of our above mentioned issuedpatent is described as preferably being an insulative member havingconductive tuning elements attached thereto, it has been foundsatisfactory to construct the rotatable cylinder of a ferrous materialand to attach to a portion of and overlying the surface thereof anon-ferrous tuning element, of the desired shape, by any known means.Alternatively, the cylinder may be made of a non-ferrous material and aportion of the peripheral surface thereof may be overlain with a ferrousmaterial.

Referring to Figures 1 and 2, the rotatable cylinder 46 may be employedin the manner of a detent-switch device whereby the cylinder snaps intoplace at each position of a tuning element adjacent the coil 56.Adjustable tuning may be provided for the tuning elements by theconstruction shown for the element 51 which comprises a cylindricallythreaded screw of ferrous or non-ferrous material having a slot 59 bymeans of which said element 51 may be varied in radial position, thusadjusting the relative proximity of the element 51 to the coil 56 whenin position with respect thereto. The center region of the spiral coil56 may be left open to provide access with the adjusting tool to thetuning element 51 in order that the tuning of the coil may be adjustedwhile said element 51 is switched in position adjacent the coil.

For a more detailed description of the mode of operation attention isdirected to our issued patent mentioned hereinabove.

While the present invention has been described in its basic form and ina preferred arrangement, it will be evident that alternative embodimentsmay be employed within the scope thereof.

What is claimed is:

Electrical tuning apparatus comprising an insulative cylinder, a coil ofconductive material formed in a spiral shape and positioned adjacent theouter surface of said cylinder, at least one conductive member offerrous material positioned adjacent the surface and occupying a portionof the periphery of and rotatable with said cylinder in axial alignmentwith said coil, at least one conductive member of non-ferrous materialpositioned in axial alignment with the position of said coil andadjacent said coil, said non-ferrous conductive member occupying aportion of said periphery of the cylinder other than the positionoccupied by said ferrous conductive member, some of said conductivemembers being radially threaded into said cylinder and having anadjustment means positioned on the outer surface thereof, and said coilhaving an opening near the center thereof through which an adjustmenttool may be temporarily inserted to engage said adjusting means on saidthreaded members.

References Cited in the file of this patent UNITED STATES PATENTS2,438,359 Clapp Mar. 23, 1948 2,489,645 Jensen Nov. 29, 1949 FOREIGNPATENTS 906,009 France Apr. 30, 1945

